Browse Prior Art Database

Liquid Safety Shutter for Lasers

IP.com Disclosure Number: IPCOM000086286D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Gaston, CA: AUTHOR

Abstract

In a light pipe coupled laser end point detection system, utilized to determine when, for example, a liquid etch is completed, the operator must be protected automatically from any inadvertent exposure to the laser beam. Obviously maximum risk occurs when the wafer is being placed in the liquid or being removed therefrom, as well as when the laser conveyance mechanism is being removed from the batch tank.

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Liquid Safety Shutter for Lasers

In a light pipe coupled laser end point detection system, utilized to determine when, for example, a liquid etch is completed, the operator must be protected automatically from any inadvertent exposure to the laser beam. Obviously maximum risk occurs when the wafer is being placed in the liquid or being removed therefrom, as well as when the laser conveyance mechanism is being removed from the batch tank.

In the drawing, one implementation of a simple, automatic light shutter to protect the eyes of the operator from the movable laser beam is illustrated. As shown, a flexible light pipe conveys a laser beam to a wafer carrier in a processing tank, in the illustrated instance for end point detection. The beam should be cut off for safety when the operator removes the wafer carrier and the light pipe from the tank. This is accomplished automatically, for as soon as the liquid drains from the angled liquid passage there is total internal reflection at interface 1, and the beam is absorbed either along the side wall 4 of the light pipe end assembly or reflected back towards its source. When immersed, however this small difference in refractive index permits transmission at interface 1, realignment of the light at 2 and 90 degrees reflection at the prism 3, and thus effects the desired horizontal output beam.

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